There is significant interest in attaching sensors to the outside of casing or tubulars in subterranean wells to provide information on the changes in the downhole environment either continuously or periodically, particularly in oil and gas well bores. However one of the challenges is the transmission of information between the sensors and the surface.
Previously, cables have been attached to the outside of casing with clamps and other mechanical devices, to transmit information from the sensors to the surface, but the size of the cables used and the mechanical fixation methods has limited the applicability of the installation.
Generally it has not been considered appropriate to attach elongated objects of a significant diameter to a well casing in the cement path because there is a risk that there will be insufficient penetration of cement in the interstices between the casing and object and between the object and the wellbore wall, which would therefore result in a leak path from formation to the surface. In turn, such a path is a risk to the integrity of the isolation from formation to surface and thus unacceptable on environmental and safety grounds.
Another challenge is that wellbore environments may have extreme conditions in terms of e.g. pressure, temperature, pH or chemical environment. This has limited the possibility to attach sensors to the outer surface of a pipe without using clamps, as the attaching mechanism must first resist such extreme conditions and then have enough flexibility to follow the axial and circumferential geometry of the pipe.
The object of the invention is to overcome the limitations of the previous methods using a tape for attaching optic fibers to the outside surface of tubulars.